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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 05-Mar-07
5    ---------------------
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
12     2. I had an email from Eric Raymond about problems translating some of PCRE's
13        man pages to HTML (despite the fact that I distribute HTML pages, some
14        people do their own conversions for various reasons). The problems
15        concerned the use of low-level troff macros .br and .in. I have therefore
16        removed all such uses from the man pages (some were redundant, some could
17        be replaced by .nf/.fi pairs). The maintain/132html script that I use to
18        generate HTML has been updated to handle .nf/.fi and to complain if it
19        encounters .br or .in.
22    Version 7.0 19-Dec-06
23    ---------------------
25     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
26        moving to gcc 4.1.1.
28     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
29        sys/time.h, which is documented as needed for this function. It doesn't
30        seem to matter on Linux, but it showed up on some releases of OS X.
32     3. It seems that there are systems where bytes whose values are greater than
33        127 match isprint() in the "C" locale. The "C" locale should be the
34        default when a C program starts up. In most systems, only ASCII printing
35        characters match isprint(). This difference caused the output from pcretest
36        to vary, making some of the tests fail. I have changed pcretest so that:
38        (a) When it is outputting text in the compiled version of a pattern, bytes
39            other than 32-126 are always shown as hex escapes.
41        (b) When it is outputting text that is a matched part of a subject string,
42            it does the same, unless a different locale has been set for the match
43            (using the /L modifier). In this case, it uses isprint() to decide.
45     4. Fixed a major bug that caused incorrect computation of the amount of memory
46        required for a compiled pattern when options that changed within the
47        pattern affected the logic of the preliminary scan that determines the
48        length. The relevant options are -x, and -i in UTF-8 mode. The result was
49        that the computed length was too small. The symptoms of this bug were
50        either the PCRE error "internal error: code overflow" from pcre_compile(),
51        or a glibc crash with a message such as "pcretest: free(): invalid next
52        size (fast)". Examples of patterns that provoked this bug (shown in
53        pcretest format) are:
55          /(?-x: )/x
56          /(?x)(?-x: \s*#\s*)/
57          /((?i)[\x{c0}])/8
58          /(?i:[\x{c0}])/8
60        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
61        is now done differently.
63     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
64        wrapper classes; (b) implement a new function in the C++ scanner that is
65        more efficient than the old way of doing things because it avoids levels of
66        recursion in the regex matching; (c) add a paragraph to the documentation
67        for the FullMatch() function.
69     6. The escape sequence \n was being treated as whatever was defined as
70        "newline". Not only was this contrary to the documentation, which states
71        that \n is character 10 (hex 0A), but it also went horribly wrong when
72        "newline" was defined as CRLF. This has been fixed.
74     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
75        was being set to -1 for the "end of line" case (supposedly a value that no
76        character can have). Though this value is never used (the check for end of
77        line is "zero bytes in current character"), it caused compiler complaints.
78        I've changed it to 0xffffffff.
80     8. In pcre_version.c, the version string was being built by a sequence of
81        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
82        string (as it is for production releases) called a macro with an empty
83        argument. The C standard says the result of this is undefined. The gcc
84        compiler treats it as an empty string (which was what was wanted) but it is
85        reported that Visual C gives an error. The source has been hacked around to
86        avoid this problem.
88     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
89        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
90        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
91        of them did).
93    10. Originally, pcretest opened its input and output without "b"; then I was
94        told that "b" was needed in some environments, so it was added for release
95        5.0 to both the input and output. (It makes no difference on Unix-like
96        systems.) Later I was told that it is wrong for the input on Windows. I've
97        now abstracted the modes into two macros, to make it easier to fiddle with
98        them, and removed "b" from the input mode under Windows.
100    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
102    12. Added -help and --help to pcretest as an official way of being reminded
103        of the options.
105    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
106        and pcrecpp.cc because they annoy compilers at high warning levels.
108    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
110    15. Fixed an occurrence of == in configure.ac that should have been = (shell
111        scripts are not C programs :-) and which was not noticed because it works
112        on Linux.
114    16. pcretest is supposed to handle any length of pattern and data line (as one
115        line or as a continued sequence of lines) by extending its input buffer if
116        necessary. This feature was broken for very long pattern lines, leading to
117        a string of junk being passed to pcre_compile() if the pattern was longer
118        than about 50K.
120    17. I have done a major re-factoring of the way pcre_compile() computes the
121        amount of memory needed for a compiled pattern. Previously, there was code
122        that made a preliminary scan of the pattern in order to do this. That was
123        OK when PCRE was new, but as the facilities have expanded, it has become
124        harder and harder to keep it in step with the real compile phase, and there
125        have been a number of bugs (see for example, 4 above). I have now found a
126        cunning way of running the real compile function in a "fake" mode that
127        enables it to compute how much memory it would need, while actually only
128        ever using a few hundred bytes of working memory and without too many
129        tests of the mode. This should make future maintenance and development
130        easier. A side effect of this work is that the limit of 200 on the nesting
131        depth of parentheses has been removed (though this was never a serious
132        limitation, I suspect). However, there is a downside: pcre_compile() now
133        runs more slowly than before (30% or more, depending on the pattern). I
134        hope this isn't a big issue. There is no effect on runtime performance.
136    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
137        newline (only possible for the last line of a file) and it was a
138        pattern that set a locale (followed by /Lsomething), pcretest crashed.
140    19. Added additional timing features to pcretest. (1) The -tm option now times
141        matching only, not compiling. (2) Both -t and -tm can be followed, as a
142        separate command line item, by a number that specifies the number of
143        repeats to use when timing. The default is 50000; this gives better
144        precision, but takes uncomfortably long for very large patterns.
146    20. Extended pcre_study() to be more clever in cases where a branch of a
147        subpattern has no definite first character. For example, (a*|b*)[cd] would
148        previously give no result from pcre_study(). Now it recognizes that the
149        first character must be a, b, c, or d.
151    21. There was an incorrect error "recursive call could loop indefinitely" if
152        a subpattern (or the entire pattern) that was being tested for matching an
153        empty string contained only one non-empty item after a nested subpattern.
154        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
155        incorrectly, because the \d was being skipped in the check.
157    22. The pcretest program now has a new pattern option /B and a command line
158        option -b, which is equivalent to adding /B to every pattern. This causes
159        it to show the compiled bytecode, without the additional information that
160        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
161        is the same as /B/I).
163    23. A new optimization is now able automatically to treat some sequences such
164        as a*b as a*+b. More specifically, if something simple (such as a character
165        or a simple class like \d) has an unlimited quantifier, and is followed by
166        something that cannot possibly match the quantified thing, the quantifier
167        is automatically "possessified".
169    24. A recursive reference to a subpattern whose number was greater than 39
170        went wrong under certain circumstances in UTF-8 mode. This bug could also
171        have affected the operation of pcre_study().
173    25. Realized that a little bit of performance could be had by replacing
174        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
176    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
178    27. Possessive quantifiers such as a++ were previously implemented by turning
179        them into atomic groups such as ($>a+). Now they have their own opcodes,
180        which improves performance. This includes the automatically created ones
181        from 23 above.
183    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
184        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
185        the first matched character to be a colon. This applied both to named and
186        numbered groups.
188    29. The ucpinternal.h header file was missing its idempotency #ifdef.
190    30. I was sent a "project" file called libpcre.a.dev which I understand makes
191        building PCRE on Windows easier, so I have included it in the distribution.
193    31. There is now a check in pcretest against a ridiculously large number being
194        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
195        loop, the loop is abandoned.
197    32. Forward references to subpatterns in conditions such as (?(2)...) where
198        subpattern 2 is defined later cause pcre_compile() to search forwards in
199        the pattern for the relevant set of parentheses. This search went wrong
200        when there were unescaped parentheses in a character class, parentheses
201        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
203    33. "Subroutine" calls and backreferences were previously restricted to
204        referencing subpatterns earlier in the regex. This restriction has now
205        been removed.
207    34. Added a number of extra features that are going to be in Perl 5.10. On the
208        whole, these are just syntactic alternatives for features that PCRE had
209        previously implemented using the Python syntax or my own invention. The
210        other formats are all retained for compatibility.
212        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
213            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
214            also .NET compatible.
216        (b) A recursion or subroutine call to a named group can now be defined as
217            (?&name) as well as (?P>name).
219        (c) A backreference to a named group can now be defined as \k<name> or
220            \k'name' as well as (?P=name). The new forms, as well as being in Perl
221            5.10, are also .NET compatible.
223        (d) A conditional reference to a named group can now use the syntax
224            (?(<name>) or (?('name') as well as (?(name).
226        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
227            groups (named and numbered) that are never evaluated inline, but can be
228            called as "subroutines" from elsewhere. In effect, the DEFINE condition
229            is always false. There may be only one alternative in such a group.
231        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
232            as the simple (?(R). The condition is true only if the most recent
233            recursion is that of the given number or name. It does not search out
234            through the entire recursion stack.
236        (g) The escape \gN or \g{N} has been added, where N is a positive or
237            negative number, specifying an absolute or relative reference.
239    35. Tidied to get rid of some further signed/unsigned compiler warnings and
240        some "unreachable code" warnings.
242    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
243        things, this adds five new scripts.
245    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
246        There were also incompatibilities regarding the handling of \Q..\E inside
247        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
248        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
250    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
251        matches an empty string, and forcibly breaks the loop. There were bugs in
252        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
253        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
254        separate and independent bugs (that affected different cases) have been
255        fixed.
257    39. Refactored the code to abolish the use of different opcodes for small
258        capturing bracket numbers. This is a tidy that I avoided doing when I
259        removed the limit on the number of capturing brackets for 3.5 back in 2001.
260        The new approach is not only tidier, it makes it possible to reduce the
261        memory needed to fix the previous bug (38).
263    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
264        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
265        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
266        mode.
268    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
269        report.
271    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
272        copy construction and assignment in the C++ wrapper.
274    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
275        couple of bugs that could have given wrong results in the "--newline=crlf"
276        case.
278    44. Added a number of casts and did some reorganization of signed/unsigned int
279        variables following suggestions from Dair Grant. Also renamed the variable
280        "this" as "item" because it is a C++ keyword.
282    45. Arranged for dftables to add
284          #include "pcre_internal.h"
286        to pcre_chartables.c because without it, gcc 4.x may remove the array
287        definition from the final binary if PCRE is built into a static library and
288        dead code stripping is activated.
290    46. For an unanchored pattern, if a match attempt fails at the start of a
291        newline sequence, and the newline setting is CRLF or ANY, and the next two
292        characters are CRLF, advance by two characters instead of one.
295    Version 6.7 04-Jul-06
296    ---------------------
298     1. In order to handle tests when input lines are enormously long, pcretest has
299        been re-factored so that it automatically extends its buffers when
300        necessary. The code is crude, but this _is_ just a test program. The
301        default size has been increased from 32K to 50K.
303     2. The code in pcre_study() was using the value of the re argument before
304        testing it for NULL. (Of course, in any sensible call of the function, it
305        won't be NULL.)
307     3. The memmove() emulation function in pcre_internal.h, which is used on
308        systems that lack both memmove() and bcopy() - that is, hardly ever -
309        was missing a "static" storage class specifier.
311     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
312        containing an extended class (one that cannot be represented by a bitmap
313        because it contains high-valued characters or Unicode property items, e.g.
314        [\pZ]). Almost always one would set UTF-8 mode when processing such a
315        pattern, but PCRE should not loop if you do not (it no longer does).
316        [Detail: two cases were found: (a) a repeated subpattern containing an
317        extended class; (b) a recursive reference to a subpattern that followed a
318        previous extended class. It wasn't skipping over the extended class
319        correctly when UTF-8 mode was not set.]
321     5. A negated single-character class was not being recognized as fixed-length
322        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
323        compile error "lookbehind assertion is not fixed length".
325     6. The RunPerlTest auxiliary script was showing an unexpected difference
326        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
327        write a Perl script that can interpret lines of an input file either as
328        byte characters or as UTF-8, which is what "perltest" was being required to
329        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
330        can't do is switch easily at run time between having the "use utf8;" pragma
331        or not. In the end, I fudged it by using the RunPerlTest script to insert
332        "use utf8;" explicitly for the UTF-8 tests.
334     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
335        the end of the subject string, contrary to the documentation and to what
336        Perl does. This was true of both matching functions. Now it matches only at
337        the start of the subject and immediately after *internal* newlines.
339     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
340        a pointer to an int instead of a pointer to an unsigned long int. This
341        caused problems on 64-bit systems.
343     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
344        instance of the 'standard' template library not being so standard".
346    10. There was no check on the number of named subpatterns nor the maximum
347        length of a subpattern name. The product of these values is used to compute
348        the size of the memory block for a compiled pattern. By supplying a very
349        long subpattern name and a large number of named subpatterns, the size
350        computation could be caused to overflow. This is now prevented by limiting
351        the length of names to 32 characters, and the number of named subpatterns
352        to 10,000.
354    11. Subpatterns that are repeated with specific counts have to be replicated in
355        the compiled pattern. The size of memory for this was computed from the
356        length of the subpattern and the repeat count. The latter is limited to
357        65535, but there was no limit on the former, meaning that integer overflow
358        could in principle occur. The compiled length of a repeated subpattern is
359        now limited to 30,000 bytes in order to prevent this.
361    12. Added the optional facility to have named substrings with the same name.
363    13. Added the ability to use a named substring as a condition, using the
364        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
365        are numbers (not recommended). Forward references are permitted.
367    14. Added forward references in named backreferences (if you see what I mean).
369    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
370        pattern could run off the end of the subject. For example, the pattern
371        "(?s)(.{1,5})"8 did this with the subject "ab".
373    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
374        PCRE_CASELESS was set when matching characters that were quantified with ?
375        or *.
377    17. A character class other than a single negated character that had a minimum
378        but no maximum quantifier - for example [ab]{6,} - was not handled
379        correctly by pce_dfa_exec(). It would match only one character.
381    18. A valid (though odd) pattern that looked like a POSIX character
382        class but used an invalid character after [ (for example [[,abc,]]) caused
383        pcre_compile() to give the error "Failed: internal error: code overflow" or
384        in some cases to crash with a glibc free() error. This could even happen if
385        the pattern terminated after [[ but there just happened to be a sequence of
386        letters, a binary zero, and a closing ] in the memory that followed.
388    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
389        over the years. Originally (before any Unicode support), just the bottom 8
390        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
391        output from "man perlunicode" includes this:
393          The regular expression compiler produces polymorphic opcodes.  That
394          is, the pattern adapts to the data and automatically switches to
395          the Unicode character scheme when presented with Unicode data--or
396          instead uses a traditional byte scheme when presented with byte
397          data.
399        Sadly, a wide octal escape does not cause a switch, and in a string with
400        no other multibyte characters, these octal escapes are treated as before.
401        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
402        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
403        Unicode string.
405        I have not perpetrated such confusion in PCRE. Up till now, it took just
406        the bottom 8 bits, as in old Perl. I have now made octal escapes with
407        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
408        translate to the appropriate multibyte character.
410    29. Applied some refactoring to reduce the number of warnings from Microsoft
411        and Borland compilers. This has included removing the fudge introduced
412        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
413        a warning about an unused variable.
415    21. PCRE has not included VT (character 0x0b) in the set of whitespace
416        characters since release 4.0, because Perl (from release 5.004) does not.
417        [Or at least, is documented not to: some releases seem to be in conflict
418        with the documentation.] However, when a pattern was studied with
419        pcre_study() and all its branches started with \s, PCRE still included VT
420        as a possible starting character. Of course, this did no harm; it just
421        caused an unnecessary match attempt.
423    22. Removed a now-redundant internal flag bit that recorded the fact that case
424        dependency changed within the pattern. This was once needed for "required
425        byte" processing, but is no longer used. This recovers a now-scarce options
426        bit. Also moved the least significant internal flag bit to the most-
427        significant bit of the word, which was not previously used (hangover from
428        the days when it was an int rather than a uint) to free up another bit for
429        the future.
431    23. Added support for CRLF line endings as well as CR and LF. As well as the
432        default being selectable at build time, it can now be changed at runtime
433        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
434        specify that it is scanning data with non-default line endings.
436    24. Changed the definition of CXXLINK to make it agree with the definition of
437        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
439    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
440        recursions. This makes a big different to stack usage for some patterns.
442    26. If a subpattern containing a named recursion or subroutine reference such
443        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
444        the space required for the compiled pattern went wrong and gave too small a
445        value. Depending on the environment, this could lead to "Failed: internal
446        error: code overflow at offset 49" or "glibc detected double free or
447        corruption" errors.
449    27. Applied patches from Google (a) to support the new newline modes and (b) to
450        advance over multibyte UTF-8 characters in GlobalReplace.
452    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
453        difference for some implementation of PCRE in some Windows version.
455    29. Added some extra testing facilities to pcretest:
457        \q<number>   in a data line sets the "match limit" value
458        \Q<number>   in a data line sets the "match recursion limt" value
459        -S <number>  sets the stack size, where <number> is in megabytes
461        The -S option isn't available for Windows.
464    Version 6.6 06-Feb-06
465    ---------------------
467     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
468        in pcreposix.h. I have copied the definition from pcre.h.
470     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
471        because pcre.h is no longer a built file.
473     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
474        not normally included in the compiled code.
477    Version 6.5 01-Feb-06
478    ---------------------
480     1. When using the partial match feature with pcre_dfa_exec(), it was not
481        anchoring the second and subsequent partial matches at the new starting
482        point. This could lead to incorrect results. For example, with the pattern
483        /1234/, partially matching against "123" and then "a4" gave a match.
485     2. Changes to pcregrep:
487        (a) All non-match returns from pcre_exec() were being treated as failures
488            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
489            error message is output. Some extra information is given for the
490            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
491            probably the only errors that are likely to be caused by users (by
492            specifying a regex that has nested indefinite repeats, for instance).
493            If there are more than 20 of these errors, pcregrep is abandoned.
495        (b) A binary zero was treated as data while matching, but terminated the
496            output line if it was written out. This has been fixed: binary zeroes
497            are now no different to any other data bytes.
499        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
500            used to set a locale for matching. The --locale=xxxx long option has
501            been added (no short equivalent) to specify a locale explicitly on the
502            pcregrep command, overriding the environment variables.
504        (d) When -B was used with -n, some line numbers in the output were one less
505            than they should have been.
507        (e) Added the -o (--only-matching) option.
509        (f) If -A or -C was used with -c (count only), some lines of context were
510            accidentally printed for the final match.
512        (g) Added the -H (--with-filename) option.
514        (h) The combination of options -rh failed to suppress file names for files
515            that were found from directory arguments.
517        (i) Added the -D (--devices) and -d (--directories) options.
519        (j) Added the -F (--fixed-strings) option.
521        (k) Allow "-" to be used as a file name for -f as well as for a data file.
523        (l) Added the --colo(u)r option.
525        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
526            is not present by default.
528     3. A nasty bug was discovered in the handling of recursive patterns, that is,
529        items such as (?R) or (?1), when the recursion could match a number of
530        alternatives. If it matched one of the alternatives, but subsequently,
531        outside the recursion, there was a failure, the code tried to back up into
532        the recursion. However, because of the way PCRE is implemented, this is not
533        possible, and the result was an incorrect result from the match.
535        In order to prevent this happening, the specification of recursion has
536        been changed so that all such subpatterns are automatically treated as
537        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
539     4. I had overlooked the fact that, in some locales, there are characters for
540        which isalpha() is true but neither isupper() nor islower() are true. In
541        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
542        and ordfeminine) are like this. This affected the treatment of \w and \W
543        when they appeared in character classes, but not when they appeared outside
544        a character class. The bit map for "word" characters is now created
545        separately from the results of isalnum() instead of just taking it from the
546        upper, lower, and digit maps. (Plus the underscore character, of course.)
548     5. The above bug also affected the handling of POSIX character classes such as
549        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
550        permanent tables. Instead, the bit maps for such a class were previously
551        created as the appropriate unions of the upper, lower, and digit bitmaps.
552        Now they are created by subtraction from the [[:word:]] class, which has
553        its own bitmap.
555     6. The [[:blank:]] character class matches horizontal, but not vertical space.
556        It is created by subtracting the vertical space characters (\x09, \x0a,
557        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
558        subtraction was done in the overall bitmap for a character class, meaning
559        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
560        be recognized. This bug has been fixed.
562     7. Patches from the folks at Google:
564          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
565          real life, but is still worth protecting against".
567          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
568          regular expressions".
570          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
571          have it.
573          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
574          "configure" and the latter not, in order to fix a problem somebody had
575          with compiling the Arg class on HP-UX.
577          (e) Improve the error-handling of the C++ wrapper a little bit.
579          (f) New tests for checking recursion limiting.
581     8. The pcre_memmove() function, which is used only if the environment does not
582        have a standard memmove() function (and is therefore rarely compiled),
583        contained two bugs: (a) use of int instead of size_t, and (b) it was not
584        returning a result (though PCRE never actually uses the result).
586     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
587        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
588        returned instead of calling malloc() with an overflowing number that would
589        most likely cause subsequent chaos.
591    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
593    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
594        with this option is matched, the nmatch and pmatch options of regexec() are
595        ignored.
597    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
598        provided in case anyone wants to the the POSIX interface with UTF-8
599        strings.
601    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
602        C++ linking (needed for some HP-UX environments).
604    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
605        (unused parameter) and in the pcre_printint() function (omitted "default"
606        switch label when the default is to do nothing).
608    15. Added some code to make it possible, when PCRE is compiled as a C++
609        library, to replace subject pointers for pcre_exec() with a smart pointer
610        class, thus making it possible to process discontinuous strings.
612    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
613        much the same function. They were added by different people who were trying
614        to make PCRE easy to compile on non-Unix systems. It has been suggested
615        that PCRE_EXPORT be abolished now that there is more automatic apparatus
616        for compiling on Windows systems. I have therefore replaced it with
617        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
618        defaults to "extern" for C or "extern C" for C++, which works fine on
619        Unix-like systems. It is now possible to override the value of PCRE_DATA_
620        SCOPE with something explicit in config.h. In addition:
622        (a) pcreposix.h still had just "extern" instead of either of these macros;
623            I have replaced it with PCRE_DATA_SCOPE.
625        (b) Functions such as _pcre_xclass(), which are internal to the library,
626            but external in the C sense, all had PCRE_EXPORT in their definitions.
627            This is apparently wrong for the Windows case, so I have removed it.
628            (It makes no difference on Unix-like systems.)
630    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
631        of recursive calls to match(). This is different to MATCH_LIMIT because
632        that limits the total number of calls to match(), not all of which increase
633        the depth of recursion. Limiting the recursion depth limits the amount of
634        stack (or heap if NO_RECURSE is set) that is used. The default can be set
635        when PCRE is compiled, and changed at run time. A patch from Google adds
636        this functionality to the C++ interface.
638    18. Changes to the handling of Unicode character properties:
640        (a) Updated the table to Unicode 4.1.0.
642        (b) Recognize characters that are not in the table as "Cn" (undefined).
644        (c) I revised the way the table is implemented to a much improved format
645            which includes recognition of ranges. It now supports the ranges that
646            are defined in UnicodeData.txt, and it also amalgamates other
647            characters into ranges. This has reduced the number of entries in the
648            table from around 16,000 to around 3,000, thus reducing its size
649            considerably. I realized I did not need to use a tree structure after
650            all - a binary chop search is just as efficient. Having reduced the
651            number of entries, I extended their size from 6 bytes to 8 bytes to
652            allow for more data.
654        (d) Added support for Unicode script names via properties such as \p{Han}.
656    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
657        matching that character.
659    20. When matching a repeated Unicode property with a minimum greater than zero,
660        (for example \pL{2,}), PCRE could look past the end of the subject if it
661        reached it while seeking the minimum number of characters. This could
662        happen only if some of the characters were more than one byte long, because
663        there is a check for at least the minimum number of bytes.
665    21. Refactored the implementation of \p and \P so as to be more general, to
666        allow for more different types of property in future. This has changed the
667        compiled form incompatibly. Anybody with saved compiled patterns that use
668        \p or \P will have to recompile them.
670    22. Added "Any" and "L&" to the supported property types.
672    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
673        but give a compile time error if the value is greater than 0xff.
675    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
676        accidentally not being installed or uninstalled.
678    25. The pcre.h file was built from pcre.h.in, but the only changes that were
679        made were to insert the current release number. This seemed silly, because
680        it made things harder for people building PCRE on systems that don't run
681        "configure". I have turned pcre.h into a distributed file, no longer built
682        by "configure", with the version identification directly included. There is
683        no longer a pcre.h.in file.
685        However, this change necessitated a change to the pcre-config script as
686        well. It is built from pcre-config.in, and one of the substitutions was the
687        release number. I have updated configure.ac so that ./configure now finds
688        the release number by grepping pcre.h.
690    26. Added the ability to run the tests under valgrind.
693    Version 6.4 05-Sep-05
694    ---------------------
696     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
697        "--" to be printed when multiple files were scanned, even when none of the
698        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
699        consider it to be a bug, and have restored the previous behaviour.
701     2. A couple of code tidies to get rid of compiler warnings.
703     3. The pcretest program used to cheat by referring to symbols in the library
704        whose names begin with _pcre_. These are internal symbols that are not
705        really supposed to be visible externally, and in some environments it is
706        possible to suppress them. The cheating is now confined to including
707        certain files from the library's source, which is a bit cleaner.
709     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
710        file's purpose clearer.
712     5. Reorganized pcre_ucp_findchar().
715    Version 6.3 15-Aug-05
716    ---------------------
718     1. The file libpcre.pc.in did not have general read permission in the tarball.
720     2. There were some problems when building without C++ support:
722        (a) If C++ support was not built, "make install" and "make test" still
723            tried to test it.
725        (b) There were problems when the value of CXX was explicitly set. Some
726            changes have been made to try to fix these, and ...
728        (c) --disable-cpp can now be used to explicitly disable C++ support.
730        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
731            backslash in a target when C++ was disabled. This confuses some
732            versions of "make", apparently. Using an intermediate variable solves
733            this. (Same for CPP_LOBJ.)
735     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
736        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
737        necessary on certain architectures.
739     4. Added a setting of -export-symbols-regex to the link command to remove
740        those symbols that are exported in the C sense, but actually are local
741        within the library, and not documented. Their names all begin with
742        "_pcre_". This is not a perfect job, because (a) we have to except some
743        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
744        available (and never for static libraries). I have made a note to try to
745        find a way round (a) in the future.
748    Version 6.2 01-Aug-05
749    ---------------------
751     1. There was no test for integer overflow of quantifier values. A construction
752        such as {1111111111111111} would give undefined results. What is worse, if
753        a minimum quantifier for a parenthesized subpattern overflowed and became
754        negative, the calculation of the memory size went wrong. This could have
755        led to memory overwriting.
757     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
759     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
760        operating environments where this matters.
762     4. Applied Giuseppe Maxia's patch to add additional features for controlling
763        PCRE options from within the C++ wrapper.
765     5. Named capturing subpatterns were not being correctly counted when a pattern
766        was compiled. This caused two problems: (a) If there were more than 100
767        such subpatterns, the calculation of the memory needed for the whole
768        compiled pattern went wrong, leading to an overflow error. (b) Numerical
769        back references of the form \12, where the number was greater than 9, were
770        not recognized as back references, even though there were sufficient
771        previous subpatterns.
773     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
774        versions of gcc, e.g. 2.95.4.
777    Version 6.1 21-Jun-05
778    ---------------------
780     1. There was one reference to the variable "posix" in pcretest.c that was not
781        surrounded by "#if !defined NOPOSIX".
783     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
784        the cross-check on the old pcre_info() function, for the benefit of the
785        cut-down version of PCRE that is currently imported into Exim.
787     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
788        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
789        patterns that start (?i) but I don't think that matters. The use of (?i) is
790        just an example; this all applies to the other options as well.
792     4. Since libtool seems to echo the compile commands it is issuing, the output
793        from "make" can be reduced a bit by putting "@" in front of each libtool
794        compile command.
796     5. Patch from the folks at Google for configure.in to be a bit more thorough
797        in checking for a suitable C++ installation before trying to compile the
798        C++ stuff. This should fix a reported problem when a compiler was present,
799        but no suitable headers.
801     6. The man pages all had just "PCRE" as their title. I have changed them to
802        be the relevant file name. I have also arranged that these names are
803        retained in the file doc/pcre.txt, which is a concatenation in text format
804        of all the man pages except the little individual ones for each function.
806     7. The NON-UNIX-USE file had not been updated for the different set of source
807        files that come with release 6. I also added a few comments about the C++
808        wrapper.
811    Version 6.0 07-Jun-05
812    ---------------------
814     1. Some minor internal re-organization to help with my DFA experiments.
816     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
817        didn't matter for the library itself when fully configured, but did matter
818        when compiling without UCP support, or within Exim, where the ucp files are
819        not imported.
821     3. Refactoring of the library code to split up the various functions into
822        different source modules. The addition of the new DFA matching code (see
823        below) to a single monolithic source would have made it really too
824        unwieldy, quite apart from causing all the code to be include in a
825        statically linked application, when only some functions are used. This is
826        relevant even without the DFA addition now that patterns can be compiled in
827        one application and matched in another.
829        The downside of splitting up is that there have to be some external
830        functions and data tables that are used internally in different modules of
831        the library but which are not part of the API. These have all had their
832        names changed to start with "_pcre_" so that they are unlikely to clash
833        with other external names.
835     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
836        a different (DFA) algorithm. Although it is slower than the original
837        function, it does have some advantages for certain types of matching
838        problem.
840     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
841        including restarting after a partial match.
843     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
844        defined when compiling for Windows was sent to me. I have put it into the
845        code, though I have no means of testing or verifying it.
847     7. Added the pcre_refcount() auxiliary function.
849     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
850        match before or at the first newline in the subject string. In pcretest,
851        the /f option on a pattern can be used to set this.
853     9. A repeated \w when used in UTF-8 mode with characters greater than 256
854        would behave wrongly. This has been present in PCRE since release 4.0.
856    10. A number of changes to the pcregrep command:
858        (a) Refactored how -x works; insert ^(...)$ instead of setting
859            PCRE_ANCHORED and checking the length, in preparation for adding
860            something similar for -w.
862        (b) Added the -w (match as a word) option.
864        (c) Refactored the way lines are read and buffered so as to have more
865            than one at a time available.
867        (d) Implemented a pcregrep test script.
869        (e) Added the -M (multiline match) option. This allows patterns to match
870            over several lines of the subject. The buffering ensures that at least
871            8K, or the rest of the document (whichever is the shorter) is available
872            for matching (and similarly the previous 8K for lookbehind assertions).
874        (f) Changed the --help output so that it now says
876              -w, --word-regex(p)
878            instead of two lines, one with "regex" and the other with "regexp"
879            because that confused at least one person since the short forms are the
880            same. (This required a bit of code, as the output is generated
881            automatically from a table. It wasn't just a text change.)
883        (g) -- can be used to terminate pcregrep options if the next thing isn't an
884            option but starts with a hyphen. Could be a pattern or a path name
885            starting with a hyphen, for instance.
887        (h) "-" can be given as a file name to represent stdin.
889        (i) When file names are being printed, "(standard input)" is used for
890            the standard input, for compatibility with GNU grep. Previously
891            "<stdin>" was used.
893        (j) The option --label=xxx can be used to supply a name to be used for
894            stdin when file names are being printed. There is no short form.
896        (k) Re-factored the options decoding logic because we are going to add
897            two more options that take data. Such options can now be given in four
898            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
900        (l) Added the -A, -B, and -C options for requesting that lines of context
901            around matches be printed.
903        (m) Added the -L option to print the names of files that do not contain
904            any matching lines, that is, the complement of -l.
906        (n) The return code is 2 if any file cannot be opened, but pcregrep does
907            continue to scan other files.
909        (o) The -s option was incorrectly implemented. For compatibility with other
910            greps, it now suppresses the error message for a non-existent or non-
911            accessible file (but not the return code). There is a new option called
912            -q that suppresses the output of matching lines, which was what -s was
913            previously doing.
915        (p) Added --include and --exclude options to specify files for inclusion
916            and exclusion when recursing.
918    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
919        Hopefully, it now does.
921    12. Missing cast in pcre_study().
923    13. Added an "uninstall" target to the makefile.
925    14. Replaced "extern" in the function prototypes in Makefile.in with
926        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
927        world, but is set differently for Windows.
929    15. Added a second compiling function called pcre_compile2(). The only
930        difference is that it has an extra argument, which is a pointer to an
931        integer error code. When there is a compile-time failure, this is set
932        non-zero, in addition to the error test pointer being set to point to an
933        error message. The new argument may be NULL if no error number is required
934        (but then you may as well call pcre_compile(), which is now just a
935        wrapper). This facility is provided because some applications need a
936        numeric error indication, but it has also enabled me to tidy up the way
937        compile-time errors are handled in the POSIX wrapper.
939    16. Added VPATH=.libs to the makefile; this should help when building with one
940        prefix path and installing with another. (Or so I'm told by someone who
941        knows more about this stuff than I do.)
943    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
944        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
945        match everything, including newlines. This is not POSIX-compatible, but
946        somebody wanted the feature. From pcretest it can be activated by using
947        both the P and the s flags.
949    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
951    19. libpcre.pc was being incorrectly installed as executable.
953    20. A couple of places in pcretest check for end-of-line by looking for '\n';
954        it now also looks for '\r' so that it will work unmodified on Windows.
956    21. Added Google's contributed C++ wrapper to the distribution.
958    22. Added some untidy missing memory free() calls in pcretest, to keep
959        Electric Fence happy when testing.
963    Version 5.0 13-Sep-04
964    ---------------------
966     1. Internal change: literal characters are no longer packed up into items
967        containing multiple characters in a single byte-string. Each character
968        is now matched using a separate opcode. However, there may be more than one
969        byte in the character in UTF-8 mode.
971     2. The pcre_callout_block structure has two new fields: pattern_position and
972        next_item_length. These contain the offset in the pattern to the next match
973        item, and its length, respectively.
975     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
976        insertion of callouts before each pattern item. Added the /C option to
977        pcretest to make use of this.
979     4. On the advice of a Windows user, the lines
981          #if defined(_WIN32) || defined(WIN32)
982          _setmode( _fileno( stdout ), 0x8000 );
983          #endif  /* defined(_WIN32) || defined(WIN32) */
985        have been added to the source of pcretest. This apparently does useful
986        magic in relation to line terminators.
988     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
989        for the benefit of those environments where the "b" makes a difference.
991     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
992        to know about it. I have put a hack into configure.in that adds in code
993        to set GCC=yes if CC=icc. This seems to end up at a point in the
994        generated configure script that is early enough to affect the setting of
995        compiler options, which is what is needed, but I have no means of testing
996        whether it really works. (The user who reported this had patched the
997        generated configure script, which of course I cannot do.)
999        LATER: After change 22 below (new libtool files), the configure script
1000        seems to know about icc (and also ecc). Therefore, I have commented out
1001        this hack in configure.in.
1003     7. Added support for pkg-config (2 patches were sent in).
1005     8. Negated POSIX character classes that used a combination of internal tables
1006        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1007        [[:^ascii]]. Typically, they would match almost any characters. The other
1008        POSIX classes were not broken in this way.
1010     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1011        to find the match, as PCRE was deluded into thinking that the match had to
1012        start at the start point or following a newline. The same bug applied to
1013        patterns with negative forward assertions or any backward assertions
1014        preceding ".*" at the start, unless the pattern required a fixed first
1015        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1017    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1018        starting at the last subject character, bytes beyond the end of the subject
1019        string were read.
1021    11. Renamed the variable "class" as "classbits" to make life easier for C++
1022        users. (Previously there was a macro definition, but it apparently wasn't
1023        enough.)
1025    12. Added the new field "tables" to the extra data so that tables can be passed
1026        in at exec time, or the internal tables can be re-selected. This allows
1027        a compiled regex to be saved and re-used at a later time by a different
1028        program that might have everything at different addresses.
1030    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1031        -R library as well as a -L library.
1033    14. The debugging options of pcretest (-d on the command line or D on a
1034        pattern) showed incorrect output for anything following an extended class
1035        that contained multibyte characters and which was followed by a quantifier.
1037    15. Added optional support for general category Unicode character properties
1038        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1039        support. It adds about 90K to the size of the library. The meanings of the
1040        inbuilt class escapes such as \d and \s have NOT been changed.
1042    16. Updated pcredemo.c to include calls to free() to release the memory for the
1043        compiled pattern.
1045    17. The generated file chartables.c was being created in the source directory
1046        instead of in the building directory. This caused the build to fail if the
1047        source directory was different from the building directory, and was
1048        read-only.
1050    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1051        file. No doubt somebody will tell me if they don't make sense... Also added
1052        Dan Mooney's comments about building on OpenVMS.
1054    19. Added support for partial matching via the PCRE_PARTIAL option for
1055        pcre_exec() and the \P data escape in pcretest.
1057    20. Extended pcretest with 3 new pattern features:
1059        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1060              write the compiled pattern to the file whose name is "rest-of-line".
1061              This is a straight binary dump of the data, with the saved pointer to
1062              the character tables forced to be NULL. The study data, if any, is
1063              written too. After writing, pcretest reads a new pattern.
1065        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1066              compiled pattern from the given file. There must not be any
1067              occurrences of "<" in the file name (pretty unlikely); if there are,
1068              pcretest will instead treat the initial "<" as a pattern delimiter.
1069              After reading in the pattern, pcretest goes on to read data lines as
1070              usual.
1072        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1073              and 16-bit fields in a compiled pattern, to simulate a pattern that
1074              was compiled on a host of opposite endianness.
1076    21. The pcre-exec() function can now cope with patterns that were compiled on
1077        hosts of opposite endianness, with this restriction:
1079          As for any compiled expression that is saved and used later, the tables
1080          pointer field cannot be preserved; the extra_data field in the arguments
1081          to pcre_exec() should be used to pass in a tables address if a value
1082          other than the default internal tables were used at compile time.
1084    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1085        now diagnosed as an error. Previously, most of the time, a negative number
1086        would have been treated as zero, but if in addition "ovector" was passed as
1087        NULL, a crash could occur.
1089    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1090        new versions from the libtool 1.5 distribution (the last one is a copy of
1091        a file called libtool.m4). This seems to have fixed the need to patch
1092        "configure" to support Darwin 1.3 (which I used to do). However, I still
1093        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1094        workstation).
1096    24. Changed the PCRE licence to be the more standard "BSD" licence.
1099    Version 4.5 01-Dec-03
1100    ---------------------
1102     1. There has been some re-arrangement of the code for the match() function so
1103        that it can be compiled in a version that does not call itself recursively.
1104        Instead, it keeps those local variables that need separate instances for
1105        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1106        needs to "recurse". Keeping track of where control must go is done by means
1107        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1108        hide most of the details from the main code, and operates only if
1109        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1110        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1111        operating.
1113        To make it easier for callers to provide specially tailored get/free
1114        functions for this usage, two new functions, pcre_stack_malloc, and
1115        pcre_stack_free, are used. They are always called in strict stacking order,
1116        and the size of block requested is always the same.
1118        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1119        PCRE has been compiled to use the stack or the heap for recursion. The
1120        -C option of pcretest uses this to show which version is compiled.
1122        A new data escape \S, is added to pcretest; it causes the amounts of store
1123        obtained and freed by both kinds of malloc/free at match time to be added
1124        to the output.
1126     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1127        what's available on my current Linux desktop machine.
1129     3. When matching a UTF-8 string, the test for a valid string at the start has
1130        been extended. If start_offset is not zero, PCRE now checks that it points
1131        to a byte that is the start of a UTF-8 character. If not, it returns
1132        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1133        this is necessary because there may be backward assertions in the pattern.
1134        When matching the same subject several times, it may save resources to use
1135        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1137     4. The code for checking the validity of UTF-8 strings has been tightened so
1138        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1139        containing "overlong sequences".
1141     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1142        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1143        should have been "&", but it just so happened that all the cases this let
1144        through by mistake were picked up later in the function.
1146     6. I had used a variable called "isblank" - this is a C99 function, causing
1147        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1149     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1150        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1151        so the version is shown; (c) stop "make test" echoing "./RunTest".
1153     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1155     9. The prototype for memmove() for systems that don't have it was using
1156        size_t, but the inclusion of the header that defines size_t was later. I've
1157        moved the #includes for the C headers earlier to avoid this.
1159    10. Added some adjustments to the code to make it easier to compiler on certain
1160        special systems:
1162          (a) Some "const" qualifiers were missing.
1163          (b) Added the macro EXPORT before all exported functions; by default this
1164              is defined to be empty.
1165          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1166              that it reads its output file name as an argument instead of writing
1167              to the standard output and assuming this can be redirected.
1169    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1170        class containing characters with values greater than 255, PCRE compilation
1171        went into a loop.
1173    12. A recursive reference to a subpattern that was within another subpattern
1174        that had a minimum quantifier of zero caused PCRE to crash. For example,
1175        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1176        recursion. If the recursively-called subpattern itself had a zero repeat,
1177        that was OK.
1179    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1180        buffer into which it was copied (for escape processing) was still set at
1181        1024, so long lines caused crashes.
1183    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1184        "internal error: code overflow...". This applied to any character class
1185        that was followed by a possessive quantifier.
1187    15. Modified the Makefile to add libpcre.la as a prerequisite for
1188        libpcreposix.la because I was told this is needed for a parallel build to
1189        work.
1191    16. If a pattern that contained .* following optional items at the start was
1192        studied, the wrong optimizing data was generated, leading to matching
1193        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1194        matching string must start with a or b or c. The correct conclusion for
1195        this pattern is that a match can start with any character.
1198    Version 4.4 13-Aug-03
1199    ---------------------
1201     1. In UTF-8 mode, a character class containing characters with values between
1202        127 and 255 was not handled correctly if the compiled pattern was studied.
1203        In fixing this, I have also improved the studying algorithm for such
1204        classes (slightly).
1206     2. Three internal functions had redundant arguments passed to them. Removal
1207        might give a very teeny performance improvement.
1209     3. Documentation bug: the value of the capture_top field in a callout is *one
1210        more than* the number of the hightest numbered captured substring.
1212     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1213        in incorrectly linking with a previously installed version. They now link
1214        explicitly with libpcre.la.
1216     5. configure.in no longer needs to recognize Cygwin specially.
1218     6. A problem in pcre.in for Windows platforms is fixed.
1220     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1221        pcretest, it used to include the size of the study block as part of its
1222        output. Unfortunately, the structure contains a field that has a different
1223        size on different hardware architectures. This meant that the tests that
1224        showed this size failed. As the block is currently always of a fixed size,
1225        this information isn't actually particularly useful in pcretest output, so
1226        I have just removed it.
1228     8. Three pre-processor statements accidentally did not start in column 1.
1229        Sadly, there are *still* compilers around that complain, even though
1230        standard C has not required this for well over a decade. Sigh.
1232     9. In pcretest, the code for checking callouts passed small integers in the
1233        callout_data field, which is a void * field. However, some picky compilers
1234        complained about the casts involved for this on 64-bit systems. Now
1235        pcretest passes the address of the small integer instead, which should get
1236        rid of the warnings.
1238    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1239        both compile and run time, and gives an error if an invalid UTF-8 sequence
1240        is found. There is a option for disabling this check in cases where the
1241        string is known to be correct and/or the maximum performance is wanted.
1243    11. In response to a bug report, I changed one line in Makefile.in from
1245            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1246        to
1247            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1249        to look similar to other lines, but I have no way of telling whether this
1250        is the right thing to do, as I do not use Windows. No doubt I'll get told
1251        if it's wrong...
1254    Version 4.3 21-May-03
1255    ---------------------
1257    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1258       Makefile.
1260    2. Some refactoring to improve the quality of the code:
1262       (i)   The utf8_table... variables are now declared "const".
1264       (ii)  The code for \cx, which used the "case flipping" table to upper case
1265             lower case letters, now just substracts 32. This is ASCII-specific,
1266             but the whole concept of \cx is ASCII-specific, so it seems
1267             reasonable.
1269       (iii) PCRE was using its character types table to recognize decimal and
1270             hexadecimal digits in the pattern. This is silly, because it handles
1271             only 0-9, a-f, and A-F, but the character types table is locale-
1272             specific, which means strange things might happen. A private
1273             table is now used for this - though it costs 256 bytes, a table is
1274             much faster than multiple explicit tests. Of course, the standard
1275             character types table is still used for matching digits in subject
1276             strings against \d.
1278       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1279             ending in _t are). So I've renamed it as ESC_tee.
1281    3. The first argument for regexec() in the POSIX wrapper should have been
1282       defined as "const".
1284    4. Changed pcretest to use malloc() for its buffers so that they can be
1285       Electric Fenced for debugging.
1287    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1288       to read one or more bytes before the start of the subject string. Often this
1289       had no effect on PCRE's behaviour, but in some circumstances it could
1290       provoke a segmentation fault.
1292    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1293       to try to read one or more bytes before the start of the subject string.
1295    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1296       UTF-8 support could misbehave in various ways if the subject string
1297       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1298       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1299       back over UTF-8 characters.)
1302    Version 4.2 14-Apr-03
1303    ---------------------
1305    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1307    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1308         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1309         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1310         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1311         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1312           and BUILD_EXEEXT
1313         Note: automatic setting of the BUILD variables is not yet working
1314         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1315           compile-time but not at link-time
1316         [LINK]: use for linking executables only
1317         make different versions for Windows and non-Windows
1318         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1319           libraries
1320         [LINK_FOR_BUILD]: new variable
1321         [OBJEXT]: use throughout
1322         [EXEEXT]: use throughout
1323         <winshared>: new target
1324         <wininstall>: new target
1325         <dftables.o>: use native compiler
1326         <dftables>: use native linker
1327         <install>: handle Windows platform correctly
1328         <clean>: ditto
1329         <check>: ditto
1330         copy DLL to top builddir before testing
1332       As part of these changes, -no-undefined was removed again. This was reported
1333       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1334       in any case.
1336    3. Some tidies to get rid of compiler warnings:
1338       . In the match_data structure, match_limit was an unsigned long int, whereas
1339         match_call_count was an int. I've made them both unsigned long ints.
1341       . In pcretest the fact that a const uschar * doesn't automatically cast to
1342         a void * provoked a warning.
1344       . Turning on some more compiler warnings threw up some "shadow" variables
1345         and a few more missing casts.
1347    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1348       option, a class that contained a single character with a value between 128
1349       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1351    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1352       option, a class that contained several characters, but with at least one
1353       whose value was between 128 and 255 caused PCRE to crash.
1356    Version 4.1 12-Mar-03
1357    ---------------------
1359    1. Compiling with gcc -pedantic found a couple of places where casts were
1360    needed, and a string in dftables.c that was longer than standard compilers are
1361    required to support.
1363    2. Compiling with Sun's compiler found a few more places where the code could
1364    be tidied up in order to avoid warnings.
1366    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1367    first of these names is deprecated in the latest Autoconf in favour of the name
1368    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1369    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1370    analogy I have changed it to CFLAGS_FOR_BUILD.
1372    4. Added -no-undefined to the linking command in the Makefile, because this is
1373    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1374    linking step for the pcreposix library.
1376    5. PCRE was failing to diagnose the case of two named groups with the same
1377    name.
1379    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1380    literal character that is needed in the subject for a match, and scans along to
1381    ensure that it is present before embarking on the full matching process. This
1382    saves time in cases of nested unlimited repeats that are never going to match.
1383    Problem: the scan can take a lot of time if the subject is very long (e.g.
1384    megabytes), thus penalizing straightforward matches. It is now done only if the
1385    amount of subject to be scanned is less than 1000 bytes.
1387    7. A lesser problem with the same optimization is that it was recording the
1388    first character of an anchored pattern as "needed", thus provoking a search
1389    right along the subject, even when the first match of the pattern was going to
1390    fail. The "needed" character is now not set for anchored patterns, unless it
1391    follows something in the pattern that is of non-fixed length. Thus, it still
1392    fulfils its original purpose of finding quick non-matches in cases of nested
1393    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1396    Version 4.0 17-Feb-03
1397    ---------------------
1399    1. If a comment in an extended regex that started immediately after a meta-item
1400    extended to the end of string, PCRE compiled incorrect data. This could lead to
1401    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1403    2. Moved to autoconf 2.53 and libtool 1.4.2.
1405    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1406    the special perltest8 script is no longer needed - all the tests can be run
1407    from a single perltest script.
1409    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1410    by \s. It has now been removed in PCRE. This means it isn't recognized as
1411    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1412    class [:space:] *does* include VT, thereby creating a mess.
1414    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1415    space and tab.
1417    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1418    its new features into the main test script, reducing the number of scripts.
1420    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1421    were backward compatible, and made the (?i) apply to the whole pattern, as if
1422    /i were given. Now it behaves more logically, and applies the option setting
1423    only to what follows. PCRE has been changed to follow suit. However, if it
1424    finds options settings right at the start of the pattern, it extracts them into
1425    the global options, as before. Thus, they show up in the info data.
1427    8. Added support for the \Q...\E escape sequence. Characters in between are
1428    treated as literals. This is slightly different from Perl in that $ and @ are
1429    also handled as literals inside the quotes. In Perl, they will cause variable
1430    interpolation. Note the following examples:
1432        Pattern            PCRE matches      Perl matches
1434        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1435        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1436        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1438    For compatibility with Perl, \Q...\E sequences are recognized inside character
1439    classes as well as outside them.
1441    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1442    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1443    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1444    signed/unsigned warnings.
1446    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1447    option for pcretest, so I've replaced it by a simple function that does just
1448    that job.
1450    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1451    "pcregrep -".
1453    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1454    Java package. This provides some syntactic sugar for simple cases of what my
1455    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1456    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1457    item, you can use this simplified notation. Note that only makes sense with
1458    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1459    greediness, whatever the setting of the PCRE_UNGREEDY option.
1461    13. A change of greediness default within a pattern was not taking effect at
1462    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1463    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1464    was abstracted outside.
1466    14. PCRE now supports the \G assertion. It is true when the current matching
1467    position is at the start point of the match. This differs from \A when the
1468    starting offset is non-zero. Used with the /g option of pcretest (or similar
1469    code), it works in the same way as it does for Perl's /g option. If all
1470    alternatives of a regex begin with \G, the expression is anchored to the start
1471    match position, and the "anchored" flag is set in the compiled expression.
1473    15. Some bugs concerning the handling of certain option changes within patterns
1474    have been fixed. These applied to options other than (?ims). For example,
1475    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1476    been the other way round. Some of this was related to change 7 above.
1478    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1479    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1480    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1481    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1483    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1484    mode. Unlike ".", it always matches newline, whatever the setting of
1485    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1486    assertions. Perl allows it, but it doesn't (in general) work because it can't
1487    calculate the length of the lookbehind. At least, that's the case for Perl
1488    5.8.0 - I've been told they are going to document that it doesn't work in
1489    future.
1491    18. Added an error diagnosis for escapes that PCRE does not support: these are
1492    \L, \l, \N, \P, \p, \U, \u, and \X.
1494    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1495    reading past the end of the pattern in cases such as /[abcd/.
1497    20. PCRE was getting more memory than necessary for patterns with classes that
1498    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1500    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1501    compiling PCRE for use with Virtual Pascal.
1503    22. Small fix to the Makefile to make it work properly if the build is done
1504    outside the source tree.
1506    23. Added a new extension: a condition to go with recursion. If a conditional
1507    subpattern starts with (?(R) the "true" branch is used if recursion has
1508    happened, whereas the "false" branch is used only at the top level.
1510    24. When there was a very long string of literal characters (over 255 bytes
1511    without UTF support, over 250 bytes with UTF support), the computation of how
1512    much memory was required could be incorrect, leading to segfaults or other
1513    strange effects.
1515    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1516    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1517    there was a subsequent back reference to those brackets. This meant that, for
1518    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1519    possible to check for precisely this case. All we can do is abandon the
1520    optimization if .* occurs inside capturing brackets when there are any back
1521    references whatsoever. (See below for a better fix that came later.)
1523    26. The handling of the optimization for finding the first character of a
1524    non-anchored pattern, and for finding a character that is required later in the
1525    match were failing in some cases. This didn't break the matching; it just
1526    failed to optimize when it could. The way this is done has been re-implemented.
1528    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1530    28. Added a new feature that provides some of the functionality that Perl
1531    provides with (?{...}). The facility is termed a "callout". The way it is done
1532    in PCRE is for the caller to provide an optional function, by setting
1533    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1534    global variable. By default it is unset, which disables all calling out. To get
1535    the function called, the regex must include (?C) at appropriate points. This
1536    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1537    This provides a means of identifying different callout points. When PCRE
1538    reaches such a point in the regex, if pcre_callout has been set, the external
1539    function is called. It is provided with data in a structure called
1540    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1541    matching continues; if it returns a non-zero value, the match at the current
1542    point fails. However, backtracking will occur if possible. [This was changed
1543    later and other features added - see item 49 below.]
1545    29. pcretest is upgraded to test the callout functionality. It provides a
1546    callout function that displays information. By default, it shows the start of
1547    the match and the current position in the text. There are some new data escapes
1548    to vary what happens:
1550        \C+         in addition, show current contents of captured substrings
1551        \C-         do not supply a callout function
1552        \C!n        return 1 when callout number n is reached
1553        \C!n!m      return 1 when callout number n is reached for the mth time
1555    30. If pcregrep was called with the -l option and just a single file name, it
1556    output "<stdin>" if a match was found, instead of the file name.
1558    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1559    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1560    pcre_exec(). This saves a malloc/free per call. The default value of
1561    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1562    when configuring.
1564    32. The default maximum size of a compiled pattern is 64K. There have been a
1565    few cases of people hitting this limit. The code now uses macros to handle the
1566    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1567    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1568    configuring. Tests 2 and 5 work only with 2-byte links because they output
1569    debugging information about compiled patterns.
1571    33. Internal code re-arrangements:
1573    (a) Moved the debugging function for printing out a compiled regex into
1574        its own source file (printint.c) and used #include to pull it into
1575        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1576        separate copies.
1578    (b) Defined the list of op-code names for debugging as a macro in
1579        internal.h so that it is next to the definition of the opcodes.
1581    (c) Defined a table of op-code lengths for simpler skipping along compiled
1582        code. This is again a macro in internal.h so that it is next to the
1583        definition of the opcodes.
1585    34. Added support for recursive calls to individual subpatterns, along the
1586    lines of Robin Houston's patch (but implemented somewhat differently).
1588    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1589    allow it to read and process whole directories in Win32. This code was
1590    contributed by Lionel Fourquaux; it has not been tested by me.
1592    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1593    used to name a group. Names consist of alphanumerics and underscores, and must
1594    be unique. Back references use the syntax (?P=name) and recursive calls use
1595    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1596    numbers. The function pcre_fullinfo() can be used after compilation to extract
1597    a name/number map. There are three relevant calls:
1599      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1600      PCRE_INFO_NAMECOUNT            yields the number of entries
1601      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1603    The map is a vector of fixed-size entries. The size of each entry depends on
1604    the length of the longest name used. The first two bytes of each entry are the
1605    group number, most significant byte first. There follows the corresponding
1606    name, zero terminated. The names are in alphabetical order.
1608    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1609    case instead of 255. Making it the same both with and without UTF-8 support
1610    means that the same test output works with both.
1612    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1613    calling malloc() with a zero argument.
1615    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1616    optimization. I've improved things by keeping a bitmap of backreferences with
1617    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1618    fact referenced, the optimization can be applied. It is unlikely that a
1619    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1620    the match to follow \n) will appear inside brackets with a number greater than
1621    31, but if it does, any back reference > 31 suppresses the optimization.
1623    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1624    of disabling numbered capturing parentheses. Any opening parenthesis that is
1625    not followed by ? behaves as if it were followed by ?: but named parentheses
1626    can still be used for capturing (and they will acquire numbers in the usual
1627    way).
1629    41. Redesigned the return codes from the match() function into yes/no/error so
1630    that errors can be passed back from deep inside the nested calls. A malloc
1631    failure while inside a recursive subpattern call now causes the
1632    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1634    42. It is now possible to set a limit on the number of times the match()
1635    function is called in a call to pcre_exec(). This facility makes it possible to
1636    limit the amount of recursion and backtracking, though not in a directly
1637    obvious way, because the match() function is used in a number of different
1638    circumstances. The count starts from zero for each position in the subject
1639    string (for non-anchored patterns). The default limit is, for compatibility, a
1640    large number, namely 10 000 000. You can change this in two ways:
1642    (a) When configuring PCRE before making, you can use --with-match-limit=n
1643        to set a default value for the compiled library.
1645    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1646        a different value is set. See 45 below.
1648    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1650    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1651    of things that can be changed at compile time. The first argument specifies
1652    what is wanted and the second points to where the information is to be placed.
1653    The current list of available information is:
1655      PCRE_CONFIG_UTF8
1657    The output is an integer that is set to one if UTF-8 support is available;
1658    otherwise it is set to zero.
1662    The output is an integer that it set to the value of the code that is used for
1663    newline. It is either LF (10) or CR (13).
1667    The output is an integer that contains the number of bytes used for internal
1668    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1672    The output is an integer that contains the threshold above which the POSIX
1673    interface uses malloc() for output vectors. See item 31 above.
1677    The output is an unsigned integer that contains the default limit of the number
1678    of match() calls in a pcre_exec() execution. See 42 above.
1680    44. pcretest has been upgraded by the addition of the -C option. This causes it
1681    to extract all the available output from the new pcre_config() function, and to
1682    output it. The program then exits immediately.
1684    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1685    order to support additional features. One way would have been to define
1686    pcre_exec2() (for example) with extra arguments, but this would not have been
1687    extensible, and would also have required all calls to the original function to
1688    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1689    is used for passing in "extra" data from pcre_study().
1691    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1692    contains the following fields:
1694      flags         a bitmap indicating which of the following fields are set
1695      study_data    opaque data from pcre_study()
1696      match_limit   a way of specifying a limit on match() calls for a specific
1697                      call to pcre_exec()
1698      callout_data  data for callouts (see 49 below)
1700    The flag bits are also defined in pcre.h, and are
1706    The pcre_study() function now returns one of these new pcre_extra blocks, with
1707    the actual study data pointed to by the study_data field, and the
1708    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1709    before. That is, this change is entirely upwards-compatible and requires no
1710    change to existing code.
1712    If you want to pass in additional data to pcre_exec(), you can either place it
1713    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1714    block.
1716    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1717    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1718    times with different match limits, until it finds the minimum value needed for
1719    pcre_exec() to complete. The value is then output. This can be instructive; for
1720    most simple matches the number is quite small, but for pathological cases it
1721    gets very large very quickly.
1723    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1724    returns the size of the data block pointed to by the study_data field in a
1725    pcre_extra block, that is, the value that was passed as the argument to
1726    pcre_malloc() when PCRE was getting memory in which to place the information
1727    created by pcre_study(). The fourth argument should point to a size_t variable.
1728    pcretest has been extended so that this information is shown after a successful
1729    pcre_study() call when information about the compiled regex is being displayed.
1731    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1732    because what follows is always an absolute path. (Later: it turns out that this
1733    is more than cosmetic for MinGW, because it doesn't like empty path
1734    components.)
1736    49. Some changes have been made to the callout feature (see 28 above):
1738    (i)  A callout function now has three choices for what it returns:
1740           0  =>  success, carry on matching
1741         > 0  =>  failure at this point, but backtrack if possible
1742         < 0  =>  serious error, return this value from pcre_exec()
1744         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1745         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1746         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1747         use by callout functions. It will never be used by PCRE itself.
1749    (ii) The pcre_extra structure (see 45 above) has a void * field called
1750         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1751         pcre_callout_block structure has a field of the same name. The contents of
1752         the field passed in the pcre_extra structure are passed to the callout
1753         function in the corresponding field in the callout block. This makes it
1754         easier to use the same callout-containing regex from multiple threads. For
1755         testing, the pcretest program has a new data escape
1757           \C*n        pass the number n (may be negative) as callout_data
1759         If the callout function in pcretest receives a non-zero value as
1760         callout_data, it returns that value.
1762    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1763    there were some redundant $(CFLAGS) in commands that are now specified as
1764    $(LINK), which already includes $(CFLAGS).
1766    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1767    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1768    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1769    one-byte characters throughout. Note that case-insensitive matching applies
1770    only to characters whose values are less than 256. PCRE doesn't support the
1771    notion of cases for higher-valued characters.
1773    (i)   A character class whose characters are all within 0-255 is handled as
1774          a bit map, and the map is inverted for negative classes. Previously, a
1775          character > 255 always failed to match such a class; however it should
1776          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1778    (ii)  A negated character class with a single character < 255 is coded as
1779          "not this character" (OP_NOT). This wasn't working properly when the test
1780          character was multibyte, either singly or repeated.
1782    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1783          mode, for example: \x{100}{2,3}.
1785    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1786          singly or repeated) now correctly test multibyte characters. However,
1787          PCRE doesn't recognize any characters with values greater than 255 as
1788          digits, spaces, or word characters. Such characters always match \D, \S,
1789          and \W, and never match \d, \s, or \w.
1791    (v)   Classes may now contain characters and character ranges with values
1792          greater than 255. For example: [ab\x{100}-\x{400}].
1794    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1795          PCRE in UTF-8 mode.
1797    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1798    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1799    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1800    value.)
1802    53. The single man page has become too large. I have therefore split it up into
1803    a number of separate man pages. These also give rise to individual HTML pages;
1804    these are now put in a separate directory, and there is an index.html page that
1805    lists them all. Some hyperlinking between the pages has been installed.
1807    54. Added convenience functions for handling named capturing parentheses.
1809    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1810    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1811    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1812    are faulted.
1814    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1815    calling configure. These values are used when compiling the dftables.c program
1816    which is run to generate the source of the default character tables. They
1817    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1818    you will need to set these values.
1820    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1823    Version 3.9 02-Jan-02
1824    ---------------------
1826    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1828    2. If --disable-static was given, the building process failed when trying to
1829    build pcretest and pcregrep. (For some reason it was using libtool to compile
1830    them, which is not right, as they aren't part of the library.)
1833    Version 3.8 18-Dec-01
1834    ---------------------
1836    1. The experimental UTF-8 code was completely screwed up. It was packing the
1837    bytes in the wrong order. How dumb can you get?
1840    Version 3.7 29-Oct-01
1841    ---------------------
1843    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1844    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1845    this didn't happen under Solaris 8, where I normally test things.
1847    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1848    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1849    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1850    this fix an hour or so after the initial 3.7 release.)
1853    Version 3.6 23-Oct-01
1854    ---------------------
1856    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1857    offsets passed as NULL with zero offset count.
1859    2. The config.guess and config.sub files had not been updated when I moved to
1860    the latest autoconf.
1863    Version 3.5 15-Aug-01
1864    ---------------------
1866    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1867    had been forgotten.
1869    2. By using declared but undefined structures, we can avoid using "void"
1870    definitions in pcre.h while keeping the internal definitions of the structures
1871    private.
1873    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1874    user point of view, this means that both static and shared libraries are built
1875    by default, but this can be individually controlled. More of the work of
1876    handling this static/shared cases is now inside libtool instead of PCRE's make
1877    file.
1879    4. The pcretest utility is now installed along with pcregrep because it is
1880    useful for users (to test regexs) and by doing this, it automatically gets
1881    relinked by libtool. The documentation has been turned into a man page, so
1882    there are now .1, .txt, and .html versions in /doc.
1884    5. Upgrades to pcregrep:
1885       (i)   Added long-form option names like gnu grep.
1886       (ii)  Added --help to list all options with an explanatory phrase.
1887       (iii) Added -r, --recursive to recurse into sub-directories.
1888       (iv)  Added -f, --file to read patterns from a file.
1890    6. pcre_exec() was referring to its "code" argument before testing that
1891    argument for NULL (and giving an error if it was NULL).
1893    7. Upgraded Makefile.in to allow for compiling in a different directory from
1894    the source directory.
1896    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1897    options bits, the pointer it was passed was to an int instead of to an unsigned
1898    long int. This mattered only on 64-bit systems.
1900    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1901    generated) instead of pcre.in, which it its source. Also made the same change
1902    in several of the .c files.
1904    10. A new release of gcc defines printf() as a macro, which broke pcretest
1905    because it had an ifdef in the middle of a string argument for printf(). Fixed
1906    by using separate calls to printf().
1908    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
1909    script, to force use of CR or LF instead of \n in the source. On non-Unix
1910    systems, the value can be set in config.h.
1912    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
1913    absolute limit. Changed the text of the error message to make this clear, and
1914    likewise updated the man page.
1916    13. The limit of 99 on the number of capturing subpatterns has been removed.
1917    The new limit is 65535, which I hope will not be a "real" limit.
1920    Version 3.4 22-Aug-00
1921    ---------------------
1923    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
1925    2. Diagnose condition (?(0) as an error instead of crashing on matching.
1928    Version 3.3 01-Aug-00
1929    ---------------------
1931    1. If an octal character was given, but the value was greater than \377, it
1932    was not getting masked to the least significant bits, as documented. This could
1933    lead to crashes in some systems.
1935    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
1936    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
1938    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
1939    These just pass their arguments on to (pcre_free)(), but they are provided
1940    because some uses of PCRE bind it to non-C systems that can call its functions,
1941    but cannot call free() or pcre_free() directly.
1943    4. Add "make test" as a synonym for "make check". Corrected some comments in
1944    the Makefile.
1946    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
1947    Makefile.
1949    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
1950    command called pgrep for grepping around the active processes.
1952    7. Added the beginnings of support for UTF-8 character strings.
1954    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
1955    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
1956    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
1957    out for the ar command.)
1960    Version 3.2 12-May-00
1961    ---------------------
1963    This is purely a bug fixing release.
1965    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
1966    of ZA. This was just one example of several cases that could provoke this bug,
1967    which was introduced by change 9 of version 2.00. The code for breaking
1968    infinite loops after an iteration that matches an empty string was't working
1969    correctly.
1971    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
1972    when matched against abbab (for example). After matching an empty string, it
1973    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
1974    caused it to match further down the string than it should.
1976    3. The code contained an inclusion of sys/types.h. It isn't clear why this
1977    was there because it doesn't seem to be needed, and it causes trouble on some
1978    systems, as it is not a Standard C header. It has been removed.
1980    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
1981    were reported on the Macintosh. The changes were from
1983      while ((c = *(++ptr)) != 0 && c != '\n');
1984    to
1985      while ((c = *(++ptr)) != 0 && c != '\n') ;
1987    Totally extraordinary, but if that's what it takes...
1989    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
1990    available. Added HAVE_BCOPY and an autoconf test for it; if neither
1991    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
1992    assumes the way PCRE uses memmove() (always moving upwards).
1994    6. PCRE is being used in one environment where strchr() is not available. There
1995    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
1996    faster code anyway.
1999    Version 3.1 09-Feb-00
2000    ---------------------
2002    The only change in this release is the fixing of some bugs in Makefile.in for
2003    the "install" target:
2005    (1) It was failing to install pcreposix.h.
2007    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2010    Version 3.0 01-Feb-00
2011    ---------------------
2013    1. Add support for the /+ modifier to perltest (to output $` like it does in
2014    pcretest).
2016    2. Add support for the /g modifier to perltest.
2018    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2019    matches null strings.
2021    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2022    pattern. Perl treats empty patterns specially - it reuses the most recent
2023    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2024    effect.
2026    5. The POSIX interface was broken in that it was just handing over the POSIX
2027    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2028    required a bigger vector, with some working space on the end. This means that
2029    the POSIX wrapper now has to get and free some memory, and copy the results.
2031    6. Added some simple autoconf support, placing the test data and the
2032    documentation in separate directories, re-organizing some of the
2033    information files, and making it build pcre-config (a GNU standard). Also added
2034    libtool support for building PCRE as a shared library, which is now the
2035    default.
2037    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2038    09 are not valid octal constants. Single digits will be used for minor values
2039    less than 10.
2041    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2042    existing programs that set these in the POSIX interface can use PCRE without
2043    modification.
2045    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2046    return all that pcre_info() returns, plus additional data. The pcre_info()
2047    function is retained for compatibility, but is considered to be obsolete.
2049    10. Added experimental recursion feature (?R) to handle one common case that
2050    Perl 5.6 will be able to do with (?p{...}).
2052    11. Added support for POSIX character classes like [:alpha:], which Perl is
2053    adopting.
2056    Version 2.08 31-Aug-99
2057    ----------------------
2059    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2060    trying to match at the startoffset position, but instead was moving forward to
2061    the next newline as if a previous match had failed.
2063    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2064    and could get into a loop if a null string was matched other than at the start
2065    of the subject.
2067    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2068    be distinguished at compile time, and for completeness also added PCRE_DATE.
2070    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2071    in GnuWin32 environments.
2074    Version 2.07 29-Jul-99
2075    ----------------------
2077    1. The documentation is now supplied in plain text form and HTML as well as in
2078    the form of man page sources.
2080    2. C++ compilers don't like assigning (void *) values to other pointer types.
2081    In particular this affects malloc(). Although there is no problem in Standard
2082    C, I've put in casts to keep C++ compilers happy.
2084    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2085    should be (const char *).
2087    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2088    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2089    However, I haven't made this a standard facility. The documentation doesn't
2090    mention it, and the Makefile doesn't support it.
2092    5. The Makefile now contains an "install" target, with editable destinations at
2093    the top of the file. The pcretest program is not installed.
2095    6. pgrep -V now gives the PCRE version number and date.
2097    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2098    causing the entire string to be ignored, instead of just the last character.
2100    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2101    non-matching string, it can take a very, very long time, even for strings of
2102    quite modest length, because of the nested recursion. PCRE now does better in
2103    some of these cases. It does this by remembering the last required literal
2104    character in the pattern, and pre-searching the subject to ensure it is present
2105    before running the real match. In other words, it applies a heuristic to detect
2106    some types of certain failure quickly, and in the above example, if presented
2107    with a string that has no trailing " it gives "no match" very quickly.
2109    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2110    other alternatives are tried instead.
2113    Version 2.06 09-Jun-99
2114    ----------------------
2116    1. Change pcretest's output for amount of store used to show just the code
2117    space, because the remainder (the data block) varies in size between 32-bit and
2118    64-bit systems.
2120    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2121    start matching at. This allows lookbehinds to work when searching for multiple
2122    occurrences in a string.
2124    3. Added additional options to pcretest for testing multiple occurrences:
2126       /+   outputs the rest of the string that follows a match
2127       /g   loops for multiple occurrences, using the new startoffset argument
2128       /G   loops for multiple occurrences by passing an incremented pointer
2130    4. PCRE wasn't doing the "first character" optimization for patterns starting
2131    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2132    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2133    the letter 'x'. On long subject strings, this gives a significant speed-up.
2136    Version 2.05 21-Apr-99
2137    ----------------------
2139    1. Changed the type of magic_number from int to long int so that it works
2140    properly on 16-bit systems.
2142    2. Fixed a bug which caused patterns starting with .* not to work correctly
2143    when the subject string contained newline characters. PCRE was assuming
2144    anchoring for such patterns in all cases, which is not correct because .* will
2145    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2146    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2147    must be retried after every newline in the subject.
2150    Version 2.04 18-Feb-99
2151    ----------------------
2153    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2154    computation of the store needed to hold the pattern was incorrect (too large).
2155    If such patterns were nested a few deep, this could multiply and become a real
2156    problem.
2158    2. Added /M option to pcretest to show the memory requirement of a specific
2159    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2161    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2162    compiled in such a way that the backtracking after subsequent failure was
2163    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2164    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2167    Version 2.03 02-Feb-99
2168    ----------------------
2170    1. Fixed typo and small mistake in man page.
2172    2. Added 4th condition (GPL supersedes if conflict) and created separate
2173    LICENCE file containing the conditions.
2175    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2176    Perl, that is the internal \ allows the delimiter to be included in the
2177    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2178    the final delimiter, add \ to the end of the pattern (to test the error).
2180    4. Added the convenience functions for extracting substrings after a successful
2181    match. Updated pcretest to make it able to test these functions.
2184  Version 2.02 14-Jan-99  Version 2.02 14-Jan-99
2185  ----------------------  ----------------------

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